1. Field of the Invention
The present invention relates to an image forming apparatus capable of suitably correcting an exposure light value in accordance with the deterioration of the sensitivity of a photosensitive member.
2. Description of the Related Art
In conventional image forming apparatus, Se, Cds and OPC (organic photoconductor) are used as materials for photosensitive members. However, when photosensitive members produced of such materials are subjected to repeated charging, charge elimination, light exposure, toner adhesion and the like, the sensitivity of said photosensitive member gradually deteriorates and does not match the initial conditions of the image forming apparatus.
Generally, image forming apparatus such as, for example, copying apparatus, are constructed such that the quality of a produced copy image is visually judged, and a service person adjusts the exposure lamp voltage, developing bias voltage to set the surface potential of the photosensitive member, or the number of produced copies is counted and when a predetermined number of copies is attained, the exposure voltage value and the like are corrected.
The aforesaid method whereby the quality of a produced copy is visually judged and the image forming conditions are then adjusted is disadvantageous insofar as it is based on a vague judgement standard. Further, the method whereby the number of copies is counted and exposure voltage value and the like are corrected when a predetermined number of copies is attained is disadvantageous in that the degree of deterioration in sensitivity of the photosensitive member varies not only in relation to the number of copies but also through operating conditions of the copying apparatus, such that over long-term operation the image forming conditions become mismatched.